This invention relates to a process for production of resinous products such as poly(vinyl silicate) resin, poly(vinyl alcohol silicate) resin and poly(vinyl acetate silicate) resin by chemically reacting a silicic acid compound with poly(vinyl acetate) polymer.
The silicic acid compound used in this process may be produced by chemical reaction of a dry alkali metal metasilicate with a mineral acid or an acid hydrogen containing salt. The white granular silicic acid is washed with water, filtered, and then air dried at 25.degree. to 75.degree. C. The white granular silicic acid was analyzed by Infrared Analysis, using the IR KBr disc method. The Infrared Analysis was very similar to that obtained with Mallinckrodt's hydrated silica except for the area which shows the presence of Si-H bonds. The Mallinckrodt's hydrated silica (SiO.sub.2.xH.sub.2 0) has a molecular weight of 60.09.xH.sub.2 O. The said silicic acid contains an active hydrogen which will reduce silver nitrate in an aqueous solution which is evidence that Si--H bonds are present.
When the said silicic acid is heated to much above 105.degree. C, silicon dioxide with a molecular weight of about 60 is produced. On further heating, it has a melting point of 1650.degree. C. In cryoscopic and ebullioscopic determination, the silicic acid produced was not soluble in any common organic solvent but was readily soluble in dilute alkali metal hydroxide aqueous solutions.
The molecular weight was determined from the boiling point elevation of said silicic acid in a 6N sodium hydroxide solution and indicated a molecular weight of 78 .+-. 25 gm/mol. This type of reactive solution normally changes the molecular species. However, this would seem to indicate the absence of a polymeric form of silicate. This analysis may indicate a possible formula of HSi(OH).sub.3 (orthosilicoformic acid) and the presence of metasilicic acid (H.sub.2 SiO.sub.3) while in solution. The orthosilicoformic acid, when dried, will lose water to form silicoformic acid (H.SiO.OH).
To produce the silicic acid compound used in these Examples it is necessary to use a dry alkali metasilicate instead of using an aqueous solution of an alkali metal metasilicate. Hydrated silica (SiO.sub.2.xH.sub.2 O) produced by any of the common known methods may be used in this instant process.
The silicic acid will chemically react with poly(vinyl acetate) polymer in the presence of an alkali compound by heating the mixture, thereby producing various resins such as poly(vinyl silicate), poly(vinyl acetate silicate), poly(vinyl alcohol silicate), and poly(vinyl alcohol). The poly(vinyl alcohol) polymer produced may be reacted chemically with silicic acid to produce poly(vinyl silicate) polymer and poly(vinyl alcohol silicate) polymer. The various polymers may be separated by using various organic and aqueous solvents.
The exact course of the reaction which take place during the process to produce the said polymer cannot be determined with 100% certainty.
When 4 parts of a poly(vinyl acetate) emulsion, containing about 2 parts by weight of poly(vinyl acetate) polymer, are mixed with 1.5 parts by weight of dry granular silicic acid and then heated in the presence of an alkali catalyst until the water evaporates and until the softening temperature of poly(vinyl acetate) polymer is reached, it produces a mixture of poly(vinyl silicate) resin, poly(vinyl acetate silicate) resin, poly(vinyl alcohol silicate) resin and poly(vinyl alcohol) polymer. About 40 to 50% of the resin produced is not soluble in any of the common poly(vinyl acetate) polymer solvents and on chemical analysis of its silicon content as silicon dioxide it contains 30 to 40% by weight of silicon dioxide. About 40 to 50% of the resin produced is soluble in the common poly(vinyl acetate) polymer solvents and on chemical analysis of its silicon content as silicon dioxide it contains 20 to 30% by weight of silicon dioxide. About 10 to 15% of the resin produced is soluble in water and on chemical analysis of its silicon content as silicon dioxide it contains about 20 to 30% silicon dioxide. About 15 to 30% of the silicic acid does not chemically react with the poly(vinyl acetate) polymer.
The resinous products produced contain various ratios of acetate, hydroxyl and silicate groups. The degree of alcoholysis and acetalization can be controlled so that resinous products having various ratios of acetate, hydroxyl, and acetal groups, are obtained.
The poly(vinyl acetate silicate) resin may be converted to poly(vinyl alcohol silicate) polymer by the use of a caustic or mineral acid catalyst in an alcohol.
The polymers and resins produced by this method may be used as coatings, adhesives and molding compounds, may be extruded in the form of tubes, rods, sheets and threads, and may be used in the production of films.
The poly(vinyl alcohol silicate) resins are quite reactive chemically. They may be reacetylated by heating with acetic anhydride in pyridine. They can also be esterified with other acids, acid chlorides, anhydrides, dibasic acids, aldehydes and ketones. They may be chemically reacted with diisocyanates, phenol-formaldehyde resins, melamine-formaldehyde resins and dimethylol urea. To decrease the water solubility, it may be chemically reacted with chromium compounds, diazo compounds, copper-ammonia complexes and zinc-ammonia complexes.